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River 'rabbits' barred from entry to Glenelg River
Revolutionary technology is preventing Australia's worst invasive fish from taking over and degrading one of southwest Victoria's most picturesque rivers.
In 2001 introduced carp were discovered in Rocklands Reservoir, a large dam on the Glenelg River that supplies the Wimmera Mallee agricultural region with water for stock, domestic and recreational purposes.
Without a decisive response, countless numbers of carp threatened to flow into the heritage-listed Glenelg River when the dam's outlets were periodically opened to replenish levels in the 400 kilometre-long waterway.
Funding
The Glenelg Hopkins Catchment Management Authority (CMA), supported by nearly $1 million from the Australian and State Governments has now developed an innovative way to block the entry of large numbers of carp to the river.
Activities
In July 2006 special screens designed by Victorian innovator Copa Water were installed on the outlet of Rocklands Reservoir, screening out all adult and juvenile carp as well as microscopic eggs and larvae.
Glenelg Hopkins CMA's River Health Manager Melody Jane said while they had invested a large amount in the technology, its benefits for the river would be far greater.
"Carp degrade waterways by competing with native fish for food and spawning sites, and by affecting habitat," Melody said.
The sophisticated new permanent screens - which are now used in Australia and the United States to remove pollutants from stormwater - are capable of screening flows of up to 600 megalitres a day. This will be vital when the Wimmera Mallee Pipeline is completed and more water is able to be returned to the Glenelg River to meet the needs of fish, waterbugs, birds and mammals.
By comparison, the temporary mesh screens initially fitted to bar carp from entering the river were high maintenance and only able to screen about 60 megalitres of water a day.
Achievements
Rigorous trials were conducted in collaboration with Monash University to verify the suitability of the technology for screening. A scale model subsequently proved it would be virtually impossible for carp of any size to penetrate the screen.
"We can now give the Glenelg River the water it needs without risking contamination," Melody said
The Glenelg Hopkins CMA now has valuable time to improve the health of the river, which is considered to be stressed. Activities such as planting native trees on riverbanks, re-snagging and removing sand slugs will improve habitat for native fish, helping them to hold their own against introduced species.
More information
- Melody Jane, River Health Manager, Glenelg Hopkins CMA: (03) 5571 2526 or m.jane@ghcma.vic.gov.au
- Glenelg Hopkins CMA
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